The present invention relates to an integrated sensor device for measuring a change in quantity of a substance to be measured, and also relates to a measuring system using the device.
Various sensors used for detecting (or measuring) the quantity (or the concentration) of a substance have been disclosed in the prior art. For example, an integrated ion sensor that has an ion sensible membrane, a signal processing circuit and a reference electrode mounted on one-chip is disclosed in Japanese Patent Laid-Open Publication No. 4-363651. This integrated ion sensor has a plurality of connection terminals for supplying power and collecting measurement results through lines connected to the terminals.
Also, the sensors disclosed in Japanese Patent Laid-Open Publication No. 6-42983 and Japanese Patent Laid-Open Publication No. 11-311615 are constructed to transmit or receive the measurement result and energy for driving the sensor by wireless communication between the sensor and outside devices.
Generally the lifetime of such sensors is finite. That is, the performance of a sensor gradually deteriorates over time as a result of its exposure in the environment in which it is located. Particularly, chemical sensors and biosensors which are used for the detection of substances are generally not stable for long periods of time. Accordingly, it is necessary to replace the deteriorated sensor and, the shorter the lifetime of the sensor, the more frequently it must be the replaced. Japanese Patent Laid-Open Publication No. 9-297832 discloses a measuring instrument that automatically decides a lifetime of a sensor and informs the necessity of replacement to a worker. This feature may be advantageous because it is troublesome for the worker to judge the deterioration of the sensor.
However, there are problems in the conventional sensors as follows:
As described in Japanese Patent Laid-Open Publication No. 6-42983, a sensor having assembly of a plurality of boards, on which electrical circuits are arranged for processing the measurement signal, involves complicated wiring and, because there are a plurality of boards the sensor is relatively large. Generally the production costs of such sensors becomes higher.
Also, even if a sensor is constructed into a single chip as shown in Japanese Patent Laid-Open Publication No. 4-363651, the sensor is connected to outside devices by wires, and thus there are manifested problems with respect to cost or reliability. Problems may include troublesome issues with respect to the replacement of sensor, the requirement of manual labor, a relatively high cost for replacement of parts, and less reliability of connection by connectors.
Further, as described in Japanese Patent Laid-Open Publication No. 9-297832, when the necessity of replacement of sensor is communicated to a worker, if the measuring instrument is used in close proximity to a worker and the sensor is located in a position that is reasonably accessible, the replacement procedure may not present a significant problem. However, when the measurement is performed in remote locations and there are no workers nearby, a worker may not even know if replacement of sensor is necessary. Also, even if the need for replacement is communicated to the worker, the worker still must travel to location of the measuring instrument. The replacement procedure results in increased cost and decreased reliability of the connectors in view of the potential for errors during the manual replacement procedure. Further, for example, if an object to be measured is dangerous medicine, the replacement of sensors may present additional issues such as exposure to the worker and, in such situations it is likely that costs associated with the replacement of sensors would likewise be increased.
Also, in common applications, the measuring instrument may be arranged in place where a hand cannot reach or it is very difficult to replace the instrument by hand. For example, when a sensor is used in places with difficult accessibility, such as underground, underwater, inside of a pipe, or in outer space the measuring instrument could not be used after the useful life of the sensor terminates. Obviously, this is fatal in detection or measurement.
On the other hand, significant investment, the expenditure of development resources and increased risk would be required for development of a sensor device that has a long lifetime and may not be necessary for replacement for a long time. These issues are particularly relevant with respect to the development of a sensible membrane. Therefore, less expensive sensors that can be manufactured by current technology, despite their short lifetime, are frequently used.
An object of the present invention is to provide an integrated sensor device which is economical due to the sensor structure being integrated into a single chip. A further object of the invention is to provide sensor with an intermediate lifetime length which is also suited for mass production. Another object of the present invention is to provide a measuring system which is able to continuously measure without manual intervention by automatically replacing a degraded sensor by a new one and to make measurements with such integrated sensor device.
An integrated sensor device of the present invention is constructed into a single integrated circuit device comprising a detection unit that has an organic membrane, the characteristics of which are changed through contact with gas or liquid containing the substance to be measured, and a converter for converting the change of the characteristics to electric signal; a control unit for processing the signal representing the measurement result from the detection unit; and an antenna unit for transmitting the signal processed by the control unit to an external location and for receiving energy necessary for the transmission and operations of the detection and control units from an external location.
An integrated sensor device according to an embodiment of the present invention is constructed into a single integrated circuit device comprising a detection unit that consists of an ion sensible FET device for measuring pH concentration in an aqueous solution and a reference electrode; a thermal sensor for correcting the measurement result of the detection unit; a control unit for processing a signal representing the measurement result from the detection unit; and an antenna unit for transmitting the signal processed by the control unit to an external location and for receiving energy necessary for the transmission and operations of the detection and control units from an external location.
According to a preferable embodiment, the control unit has memory for pre-storing correcting information to correct the measurement result of the detection unit, and in operation, the control unit corrects the measurement result in accordance with the correcting information and transmits the corrected measurement result from the antenna unit.
Also, there is provided a reading device which comprises an antenna unit for receiving the measurement result (or corrected measurement result) transmitted from the integrated sensor device of the present invention and for transmitting energy to be supplied to the integrated sensor device; and a display unit for displaying information on the measurement result received from the integrated sensor device through the antenna unit.
A measuring system of the present invention comprises the integrated sensor device as mentioned above; a container for storing a plurality of the integrated sensor devices; an actuator for actuating a predetermined number of the integrated sensor devices stored in the container to be usable and for removing the deteriorated integrated sensor devices; a controller for controlling operation of the actuator based on the decision of whether performance of the integrated sensor device is deteriorated or whether a predetermined time for use terminates; and an antenna unit for receiving the measurement result transmitted from the integrated sensor device in use and for transmitting energy to be supplied to the integrated sensor device.
In a measuring system of the present invention, a plurality of containers, each of which stores the integrated sensor device one by one, may also be used. Preferably, each container has a seal to prevent invasion of gas or liquid from the external environment prior to use, or has absorbent inside to absorb a substance that may deteriorate the integrated sensor device.
For example, a plurality of containers, each of which has a lid partly or wholly made by a thin membrane for sealing the integrated sensor device are provided, together with a gas or a liquid to maintain the integrated sensor device stable may be used.
According to the present invention, there is also provided a container device which comprises storage for storing a plurality of the integrated sensor devices in a sealed condition, or each integrated sensor device may be individually sealed.
According to the integrated sensor device of the present invention, the measurement result of the detection unit is processed by the control unit which is then transmitted to the outside through the antenna unit. The energy necessary for the transmission and the operation of the detection unit and the control unit is supplied through the antenna unit. That is, the transmission of the measurement result and the energy to be supplied are performed by wireless transmission. Therefore, even if the measuring point is changed, it is possible to flexibly correspond to the new measuring point. Also, since the integrated sensor device is constructed into a single integrated circuit device comprising a detection unit, a control unit and an antenna unit, it has a relative small size and the wiring required to connect each unit is also incorporated, which is more suitable for mass production.
As the integrated sensor device of the present invention is constructed into a single chip, the cost can be reduced. Furthermore, because it realizes the transmission and the supply of energy by wireless, problems with respect to the reliability of the connection are reduced and the replacement of the sensor device is easily performed.
In the measuring system of the present invention, the actuator may actuate a predetermined number of the integrated sensor devices stored in the container to be usable. The transmitting and receiving unit may receive the measurement result transmitted from the integrated sensor device when in use and transmit the energy to be supplied to the integrated sensor device. If the performance of the integrated sensor device deteriorates, the controller may decide that the deterioration of performance is significant and activate operation of the actuator. The actuator may then control the removal of the deteriorated integrated sensor device and activate one of the unused integrated sensor devices. That is, the deteriorated integrated sensor device is automatically replaced by a new sensor. Therefore, manual operation is not necessary for the replacement of sensor device. Furthermore sensor devices having short lifetime can be used which, upon deterioration, can be promptly replaced thereby making it possible to realize a continuous measurement for a long period of time without use of the sensor device having long lifetime.
The measuring system of the present invention can be applied even in a place where the manual replacement is difficult or impossible.
Further, the storage of the integrated sensor device in the container can realize the all-purpose measuring system permitting use in many kinds of applications and with a wide range of sensor devices.